Help – Does anyone know what this is?

Mysterious Item – Picture 1
The assistant curator of The Dacorum Heritage Trust needs some help to identify this item. Please comment on this page or email us.
Measures 9cm (3 1/2 inches) in length It is made of some sort of metal material and the clear part is like a soft plastic.
Comments so far have been of the following:

Mysterious Item – Picture 2
It would have been helpful to show the item against a ruler (or half crown piece!) to get some idea of scale. Also, it seems to be made of wood with a metal cap end – is that the case? One theory is that it is some kind of electrical circuit unit.
By Jennifer McCann
On 27/09/2011

Mysterious Item – Picture 3
It may help identification if you said where it came from. However it could be part of a machine where the this roller guided parallel strips of some material – for example cloth ribbons, or strips of movie film during processing.
By Brian Porter
On 25/10/2011

Mysterious Item – Picture 4
Thank you in advance for your help on this.
By Bill Koolen

Mysterious Item – Picture 5